If you are lucky enough to have decent eyesight, you probably presume that you are seeing the world as it really is. But the truth is that your perception of the world around you is always defined by the limitations of human eyesight. Many animals see the world in an entirely different way. Some can see further than us while others benefit from better night vision. Now, new research has revealed for the first time exactly how birds see the world around them.
Three primary colours
Human vision is based on just three primary colours; red, green and blue. However, birds can also see ultraviolet. This means that they can perceive colour contrasts which are invisible to us. Scientists at have been working on ways to demonstrate how birds see and they have achieved impressive results.
Seeing in ultraviolet
Some things on Earth reflect ultraviolet (UV) light as well as visible light. We don't notice this, thanks to the triple-cone structure of our eyes. Birds' eyes boast an additional cone which enables them to see UV as colour. So, we have known for some time that birds can see differently to us but if we can't see in the same way, how can we understand how they perceive the world?
Ground-breaking research into avian vision
founded the Lund Vision Group at Lund University with the aim of unravelling such mysteries. The group has conducted a study into avian vision in collaboration with Cynthia Tedore who is now working at the University of Hamburg. The ground-breaking research involved the use of a unique camera which was equipped with special filters. This was able to imitate the colour sensitivity of the four different cones in avian retinas. In revealing what birds can see, the images produced by the camera have provided an amazing insight into how birds experience the world and fly more safely.
A forest of colour
A dense forest of trees appears to be simply a bank of green to humans. Birds see foliage in a completely different way and can perceive contrasts in the foliage which are completely lost on us. As birds can see ultraviolet, the undersides of leaves appear much darker than the upper sides. Birds see foliage in three dimensions and greater clarity. Where humans see one colour, birds see a variety of shades. Green is the colour which offers the worst contrasts to the human eye but does not present such difficulties to our feathered friends. The unique quality of avian visions enables birds to move about safely, navigate efficiently and find food more easily. They can tell one tree from another when the trees would appear identical to us.
The next time you are walking in the woods, find somewhere quiet to sit and spend a little time watching the birds fly about the trees. It soon becomes apparent that they have special abilities and can navigate the foliage with amazing precision.